Igniter for internal-combustion engines



y Sept. l0;1946.l E. D. cHAPLlN IGNITER yFOR NTERNAL-COMBUSTION ENGINES Filed Feb. 3.V 1944 llllllllllll Patented Sept. 10, 1946 IGNITER FOR IN TERNAL-COMBUSTI'ON ENGINES Edwin D.A Chaplin, New York, N..

B. Albert, New Yor Y, N. Y.

Harry Y., assigner to imputation February s, 1944;, serial No. 520,871

1,6 claims. (c1.l 12s-145) l This invention relates to igniters ior internal com ustion engines for controlled timing of igages by means of incandescent heaters of the high resistance and induced current types though it is noted that in some of the claims the invention is not limited to heaters utilizing any particular kind of current n or even t0 electric heaters.

One object of the invention is to provide an improved device or apparatus of this kind which retains a blanket of spent gases over a heatingelementto prevent ignition of fresh gases until the latter have been compressed to the degree necessary for efdoient operation of the engine and which prevents contact of the gases with any heater Wires.

Other objects of the invention are to provide an improved device of this kind which requires no moving parts, eliminates spark gaps and their attending corrosion and pitting, and is effective over a wide pressure range for a given requirement of electrical energy.

Sincey a large proportion are due to spark; failure resulting from sliding ject to provide a device which may form a. part of an ignition system having no moving contac-ts and referred to later in the description.

' Additional objects of fect simplicity and efficiency in such apparatus and to provide an extremely simple and compact device or apparatus of this kind which is economical, durable, and reliable in operation, and economical to manufacturel and maybe installed in a conventional cylinder head.

Still other objects of the invention will appear as the description proceeds; and while herein details of the invention are described in thek specication and some ofthe. claims, the invention as described in some of the broader claims is not limited to these, and many andy various changes may be made without departing Afrom the scope of the invention as claimed in the broader claims.

The inventive features ior the accomplishment of these and other objects are shown herein in connection with an igniter which brieiiy stated, includes a cylindrical casing having thev inner end thereof adapted to be screwed into. the cylinder head of a. motor and an igniter tube mounted in the outer end of the casing and spaced from the inner walls thereof to leave a dead air space asY a heat insulator around the tube.

the invention are to ef'- h threadably In the accompanying drawing showing, by way of example several of many possible embodiments of theinvention,

Fig. 1 is a longitudinal sectional view, partly in elevation showing one form of the invention;

Fig.Y 2 is a fragmental side view showing one form o f the igniter tube;

Fig. 3 is a fragmental sidev View showing another form of the-igniter tube; and

Fig. 4 is a fragmental longitudinal sectional view partly in elevation showing another form of the casing.

In the drawing al substantially cylindrical socket member I0 provided with a bore I I throughout has. its inner end I2 of reduced diameter and provided with exterior threads I4 whereby said inner end may be Ithreaded into a hole in the cylinder head I5-of an internal combustion engine. The exterior of the socket member adjacent said inner end is provided with lateral tool receiving faces I6 for screwing the inner end in said cylinder head. The outer end of the bore I I is surrounded by an annular seat I9 surrounded by a wall I8 provided with internal threads 20 receiving a hollow cylinder or thimble 2I of drawn steel or other suitable material in axial alinement with the socket member to form a casing, generally designated II the internal diameter of the cylinder being greater than that of the bore II.

A cylindrical heating element generally designated as 22 comprising a non-fusible and noncombustible tube 24 is disposed within the hollow ofthe cylinder in axial alinement with the bore II, the internal diameter of the tube preferably being equal to that of the bore. The exterior of the tube is wound with a coil of wire 25, the turns of the coil being electrically insulatedv from each other as by Spacing if the wire is bare or by heat resisting insulation to prevent a short circuit between adjacent turns. The en d portions 26 of the coil may be. anchored in any suitable manner such as by passing them through holes 28 in lugs 29 cast on the tube. The inner end of the tube is disposed gas-tight against. a packing ring-30 of asbestos or other suitable refractory material in the seat I9 while the outer end similarly engages a packing washer 3| of similar material urged inwardly bya plug 32 threaded in the outer end 0f the cylinder b .y means ci threads 34. The length of the bore l Iy and tube 24 and the thickness and inside diameter of the washer determine the volume of the space receiving the gases forced from the outer end of the cylinder and consequently the extent to which incoming explosive mixtures will enter the igniter when they are compressed. Varying the thickness of the washer adjusts this space. For some mixtures better resultswould be obtained by the use of a thin a thick one would serve better. The plug may be provided witha tool receiving opening or slot 35.

The cylinder is preferably provided with a pair of holes 38 in its mid-section through which pass bolts 39 having wide heads 40 welded to the wire end portions 26. Refractory insulating packing lil surrounds the shank of the bolt and hard refractory insulating washers 42 at each end engage the packing. An outer ynut 44 on the bolt draws the head and washers tightly against the.

packing to expand it against the hole walls and bolt thereby forming a gas-tight fit, the bolts being insulated from the cylinder. Conducting leads (not shown) may be connected to the screws in any well known manner. If desired, one of the ends of the coil may be grounded so that only one bolt will be required. The plug 32 may be made integral with the cylinder 2l if the cylinder and socket I are separate and the socket member and cylinder may be integral if the plug is separate. An annular space 45 is provided between the heater and the internal walls of the cylinder both to allow space for the mounting of the bolts and to insulate the heater from the cylinder. The gas therein is stagnant since the packing 30 and 3l and tube are substantially impervious.

In one form of the invention the tube or support 24 may be of refractory insulating material such as silicon carbide or fused alumina, otherwiseknown to the trade as Carborundum and Alundum. If desired, the tube, as the 24a (Fig. 2) may be provided with an external helical groove 4S in which bare high resistance wire 25a is wound.

In another form of the invention the supporting member may comprise a tube 24h (Fig. 3) of conducting material such as copper or bronze as a at Fig. 3 and the coil may be of coarse insulated low-resistance wire 25h so that for a given length of the supporting member the number of ampereturns may be large. Current supplied to this form of the coil is preferably alternating or high frequency current so that eddy currents will be induced in the tube 2M) and thereby cause it to heat up to ignition temperature. The tube 24h may be of magnetic material such as steel or iron so that heat is developed in the tube not only by means of eddy currents but by hysteresis losses in the form of heat when alternating current is used. When a tube of conducting material is used itis preferable to provide a sheath A9 of asbestos or other suitable refractory insulating material intermediate of the tube and coil for thermal insulation of the wire from the conducting tube as well as for electrical insulation. The tube 24h serves as a one-turn secondary of an inductional heater while the coil of wire wound on the tube but insulated therefrom acts as the primary winding. Alternating current applied to the coil or primary winding induceg a current toow in the tube 24h so that the latter is heated by induction to a temperature sufficient to cause ignition of the fuel mixture. Since the tube 241) is of material such as copper or bronze any heat developed in it is rapidly conducted to the inner face of the tube to heat the gases or fuel mixture thereat.

Advantages of alternating current operation of the device are due in part to the fact that .54 and terminal bolt the current can be supplied by alternators having permanent magnet rotors so that no brushes are required throughout the entire ignition system. I-Ience with my ignition device it is possible to eliminate all sliding contacts and air gaps which account for the great majority of ignition and motor failures. Furthermore my igniter may be operated at low voltages so that current leakages due to moisture on insulators, or moisture laden air between conductors, while a serious problem in conventional high tension ignition, are practically nil in my system.

The tube substantially prevents circulation of gases in the gas space to and from the major portion of the bore and the combustion zone so that the coil is not subjected to contact with fresh cool gases andthe gas within the space acts as a heat insulating blanket to keep the heater hot and the thimble il! cool.

The tube 2M may be of silicon carbide or alumina so as to be highly resistant to heat and at the same time be mechanically strong to withstand pressure differences set up between the gas space exterior and interior of the tube. In addition alumina acts as a catalyst for the transformation of hydrocarbon fuels to forms having a lesser tendency to knock.

In still another form of the invention as shown in Fig. 4, the casing Ila, is preferably integral and provided with only one terminal bolt hole 38a through which passes the bolt 39 as shown in Fig. 1. The heater 22 disposed `gas tight against the ring 3u within the hollow portion of the casing is similar to that shown in Fig. 1. A washer Sla of refractory gas tight packing is disposed against the outer end of the heater followed by a disk as silica, alumina, or silicon carbide.

One of the end portions of the coil passes through small registering holes 5l and 52 in the washer and disk respectively, thence in a radial groove 5 in the outer face of the disk from the hole 52 to the central portion of the disk. Carborundum cement or other suitable material may be employed to prevent gas leakage through the hole 5l. A cap 32a provided with a central recess hole 55 is threaded onto the outer end of the casing by means of threads 34a so that the disk is urged inwardly to clamp the heater between the ring and washer. The cap is preferably built up with a boss about the hole 55 and the latter fitted with a terminal bolt 56 in the manner described of bolts 39 and the coil end 25a welded thereto.

In operation when the motor cylinder is cleared of exhaust gases the purging of gases from the bore of the casing is not complete and spent gases remain therein. Consequently when an ignitible fuel mixture is drawn or injected into the engine cylinder the spent gases prevent the combustible mixture from coming in contact with the heater until the fuel gases are compressed during the compression stroke and the spent gases are forced to the outer end portion of the thimble 2l. By varying the capacity of the outer end portion of the bore by means of the plug 32 and washer 3l the time of contact between the fuel gas and the heater with respect to piston position can be varied to give the best operating position. Ignition takes place when a fuel mixture of proper composition is raised to its ignition temperature by heat of compression and heat supplied to the mixture by the heater tube.

The invention claimed is:

1. An igniter for gaseous mixtures, said igniter of hard refractory material suchl against the outer end of I threaded into the outermost end portion of the assaut comprisingl a casing; therein and adapted a primary coil of wire toybe exposed` to the gases; inductively coupledwith the core so that a flow of alternating current in contact with the Wire.

3. In combination, a substantially cylindrical casing closed at its outer end and provided with a bore, the casing having the inner end thereof of reduced diameter and provided with exterior threads whereby said inner end may be threaded into a hole in the cylinder head of an internal the bore of the casing being of further diameter to receive said tube and to form a tubular gas space between the tube and the inner Walls of the casing; and gas-tight means between the outer end of the tube and the interior wall of' the closed end of the casing to substantially prevent passage of gases to and from the gas space.

4. An igniter comprising a substantially cylindrical socket member provided with a bore a conductiveA secondary core throughout, said bore being of increased diameter l central portion of the seat; a coil of high resistameter of the thimble being of sufcient diameter -to receive said coil and to form a tubular gas space between the coil and the inner'walls of the thimble; the thimble holes; conducting bolts in said holes and welded to the end portions of said wire; packing between said bolts and the walls of said hole,- a washer of refractory insulating material disposed. gas-tight said tube; and a plug thimble and engaging the washer.

ble being of sufliclent diameter to receive said being provided with radial cnil and. to form-a tubular sas. space between the coil; and the inner walls of the thimble; and

means at the Qlvlter end of the thimble to substantially prevent: Passage of gases to and from said gas space and the interior of the tube.

6,. An igniter comprising a cylindrical casing outer end of the heater;

insulating material in the bore and disposed gas- Y tight against the outer face of the packing, the

with a radial groove in the outerfgace thereof; 'one of the wire end portions passing gas tight through the outer marginal portion of the packing and the disk and extending in the radial groove to the center of the disk; a cap mounted on the outer end of the casing; a terminal bolt passing gas-tight through the cap the head of the bolt bcthe cap, the inhead engaging against the outer face of the disk and the wire end portion welded to the head.

7. An ignition device comprising a substantially cylindrical socket member provided with a bore disk being provided throughout, said bore being of increased diam-l eter toward the outer end engaging the washer.

claim 7 and having a metallic tube of refractory insulating 8. A device as in tube Within( said material.

9. An `ignition device comprising, in combina-r tion, a substantially cylindrical casing provided with a bore throughout, the casing having t'he inner end thereof of reduced diameter and provided with exterior threads whereby said inner endmay be threaded into a hole in the cylinder head of an internal combustion engine; said bore beingU ofA increased diameter toward the 'outer end of the casing to form an annular seat; a hollow cylindrical heating element Within the bore in axial alinement with the casing and engaging gas-tight against said seat; a tube of refractory insulating material and engaging said ledge; a coil of wire wound on said tube; the outer portion of the bore of the casing being of suilicient diameter to receive said coil and to form a tubular gas space between the coil and the inner walls ofthe casing; a washer in the outer end of the casing and disposed gas-tight against the outer end of the tube and a hard refractory disk thereagainst, one end portion of said wire passing through the outer marginal portion of the disk and washer; a plug threadedin said bore to close the outer end of the casing.

of the casing to form an annular seat 10. An ignition device comprising in combination, a substantially cylindrical casing provided with a bore throughout, the casing having the inner end thereof of reduced diameter and provided Ywith exterior threads whereby said inner end may be threaded into a hole in the cylinder head of an internal combustion engine; said bore being of increased diameter toward the outer end outer of the engine cylinder; a tubular cylindrical heating element within the outer end of the bore in axial alinement with the casing and engaging `gas tight against said seat, said heating element comprising, a tube of refractory insulating material; a coil of wire wound on said tube; electrically conducting means connected to the ends of said coil the outer portion oi the bore oi the casing being of increased diameter to receive said coil and to form a tubular gas space between the coil and the inner walls of the casing; a washer in the outer end of the casing and disposed gas-tight against the outer end oi the tube; and closure means on the outer end of the casing engaging against the outer face of the washer for closing off the hollow of the tube from the atmosphere exterior of the engine cylinder and ignition device.

il. An ignition device comprising in combination, a substantially cylindrical casing provided with a bore throughout, the casing having the inner end thereof adapted to be mounted in a hole in the cylinder head of an internal combustion engine; a hollow cylindrical electrical heating element within the outer end of the bore the bore thereby providing a deep pocket Where spent gases tend to remain stagnant during operation of the engine; the outer portion of the bore of the ceive said element and toy form a tubular gas space between the element and the inner walls of the casing; and closure means on the outer end of the casing for closing olf the bore from the'atmosphere exterior of the engine cylinder and ignition device.

l2. An ignition device comprising in combination, a substantially cylindrical casing provided with a bore throughout, the casing having the inner end thereof adapted to be mounted into a hole in the cylinder head of an internal combustion engine; an electrical heatingelement within the outer end of the bore; said heating element comprising a support of fused alumina and a coil of wire wound on said support, the support being exposed to the fuel gases in the engine, and closure means on the outer end of the casing for closing off the bore from the atmosphere exterior of the engine cylinder and ignition device.

13.'An ignition device comprising in combination, a substantially cylindrical casing provided with a bore throughout, the casing having the inner end thereof adapted to be mounted in a casing being of increased diameter to re' `cally conducting hole in the cylinder head of an internal combustion engine; an electrical heating element within the outer end of the bore; said heating element comprising, a supporting member of refractory silicon carbide and a coil of wire wound thereon; and closure means on the outer end of the casing for closing oir the bore from the atmosphere exterioi` of the engine cylinder and ignition device.

14. An ignition device for internal combustion engines comprising structure forming a chamber and having an open end portion adapted to be mounted in a hole in the cylinder head of the engine; an electrical transformer inductional heater mounted within said chamber, said heater comprising a primary inductive winding for producing a magnetic field and having terminal ends adapted to be connected to a source of alternating current, a closed secondary exposed to the gases in the chamber and associated with the primary winding so that the building up and decay of said field will induce an electric current to flow in the closed secondary thereby producing heat in the secondary.

l5. An ignition device comprising in combination, a substantially cylindrical casing provided with a bore throughout, the casing having the inner end thereof of reduced diameter and provided with exterio-r threads whereby said inner end may be threaded into a hole in the cylinder head of an exterior combustion engine; said bore being of increased diameter toward the outer end of the casing to form an annular seat outer of the engine cylinder; a tubular cylindrical heating element within the outer end of the bore in axial alinement with the casing and engaging gas tight against said seat, said heating element comprising, a tube of refractory insulating material; a coil of wire wound on said tube; electrinieans connected to the ends of said coil, the outer portion of the bore of the casing being of increased diameter to receive said coil and to form a vtubular gas space between the coil and the inner walls of the casing; a washer in the outer end of the casing and disposed gastight against the outer end of the tube; and closure means on the outer end of the casing engaging against the outer face of the washer for closing oii the hollow of the tube from the atmosphere exterior of the device, the hollow of said tubular element and bore being much longer than the diameter thereof to provide a deep narrow recess in which spent gases remain after an exhaust vstroke in normal operation of said engine, said gases substantially covering the inner surface of tubular element until they are compressed into the outer end of the tube by compression of an air-fuel mixture and expose said surface to said mixture.

16. An igniter as in claim l, said core being of magnetic material.

EDWIN D. CHAPLIN.

engine cylinder and ignition` 

